By Ryan Struyk, CNN

(CNN) -- A majority of Americans think President Donald Trump will lose his re-election bid in 2020, according to a new CNN poll conducted by SSRS, similar numbers to those facing former President Barack Obama at this point in his first term ahead of his re-election victory.

Fifty-four percent of Americans say they expect Trump to lose his campaign for re-election, the same number who said Obama would lose the 2012 election at this point in his first term. Only 40% of Americans think Trump will win in 2020, similar to the 44% who said the same for Obama.

Republicans overwhelmingly say they expect Trump to win re-election to the White House in 2020 (79% feel that way), while Democrats nearly unanimously say they expect him to lose (87% say so). A majority of independents also expect him to lose. Republicans now are more optimistic about Trump's re-election prospects than Democrats were about Obama (just 69% of Democrats said they expected Obama to win at this point in 2010).

Former President Bill Clinton faced even worse expectations in 1995, when only a quarter of Americans expected him to win his second term following deep losses for his party in the 1994 midterm elections. Trump filed re-election paperwork with federal election officials on Inauguration Day in 2017. He formally announced his re-election bid in February.

Republican presidential primary 2020

Trump holds strong support among his own party's potential voters in a 2020 primary race. Three-quarters of Republicans and Republican-leaning independents, 75%, say they think the GOP should re-nominate Trump in 2020. Only one in five, 20%, say the GOP should nominate a different candidate. These numbers are virtually identical to Obama's support among Democrats at this point in his term.

But when those who want to see someone else take the party's nomination are asked to name an alternative to Trump, no potential candidate has a clear edge. None of the potential nominees raised by respondents earn more than 1% support; that list includes Vice President Mike Pence, former GOP nominee Mitt Romney, House Speaker Paul Ryan, Texas Sen. Ted Cruz, television personality Oprah Winfrey and retiring South Carolina Rep. Trey Gowdy.

Speculation about a Republican primary challenge has swirled around some anti-Trump GOP voices like Ohio Gov. John Kasich, outgoing Arizona Sen. Jeff Flake and Nebraska Sen. Ben Sasse, who have refused to rule out a run for the White House.

Democratic presidential primary 2020

Former Vice President Joe Biden holds the most widespread support when potential Democratic primary voters are asked to rate the chances they would support six possible candidates for the party's 2020 nomination.

A broad 84% of Democrats and Democratic-leaning independents say they are likely to support a Biden bid for the Democratic nomination, two-thirds of whom say they are "very likely" to back his candidacy.

Large majorities of Democrats and Democratic-leaning independents also say they are likely to support Vermont Sen. Bernie Sanders (75%) and Massachusetts Sen. Elizabeth Warren (68%). Still, this support is slightly less intense than Biden's: Six in 10 likely Sanders backers say they are "very likely" to support him and less than half of Warren's likely supporters say they are "very likely" to support her.

Both Biden, 75, and Sanders, 76, have not ruled out bids for the White House in 2020. Warren has said she isn't running.

About half of potential Democratic primary voters say they are likely to back California Sen. Kamala Harris, New Jersey Sen. Cory Booker and New York Sen. Kirsten Gillibrand. Roughly one in five say they aren't sure if they'd support those latter three, lesser-known possible candidates. Only two in 10 potential Democratic voters overall say they are "very likely" to back Harris and Booker; only one in 10 are "very likely" to support Gillibrand.

Sanders still has the strongest grip on young voters in the Democratic party: 60% of potential Democratic primary voters under 35 say they are very likely to back Sanders vs. 52% for Biden, 29% for Warren, 18% for Harris, 16% for Booker and 12% for Gillibrand.

Among potential Democratic primary voters, racial divisions also play a role. Six in 10 nonwhites, 61%, say they are very likely to back Biden's candidacy vs. 52% of whites who say the same. On the flip side, 39% of whites are very likely to back Warren's bid vs. only 25% of nonwhites.

The CNN poll was conducted by SSRS March 22-25 among a random national sample of 1,014 adults reached on landlines or cellphones by a live interviewer. Results for the full sample have a margin of sampling error of plus or minus 3.7 percentage points. It is larger for subgroups.